1. Field of the Invention
The present invention relates to a data line driver of a plane type display apparatus such as a liquid crystal display (LCD) apparatus.
2. Description of the Related Art
In a plane type display apparatus including a panel having data lines (or signal lines), scan lines (or gate lines) and cells each located at one intersection between the data lines and the scan lines, a data line driver is provided for driving the data lines, and a scan line driver is provided for driving the scan lines.
In order to improve the quality of a moving image, i.e., in order to remove the effect of a residual image of a moving image, the data line driver switches a gradation voltage with a black voltage (see: JP-2001-60078-A). For example, the data line driver includes a switch circuit for applying a black voltage instead of the output signals of an output buffer to data lines (see: FIG. 2 of JP-2001-60078-A) or a switch circuit for generating black data instead of the output signal of a data register (see: FIG. 3 of JP-2001-60078-A). This will be explained later in detail.
In the above-described prior art data line driver, however, since the black voltage or the black data is usually fixed, it is impossible to apply a definite non-video gradation voltage to the data lines. Note that such a definite non-video gradation voltage may be requested by customers, i.e., display apparatus manufacturers. In this case, if the black voltage or black data is generated from a variable power supply voltage generating circuit or a plurality of definite non-video gradation voltage generating circuits, the size of the data line driver is further increased.